Central Limit Order Book

A CLOB (Central Limit Order Book) is the exchange-style marketplace at the heart of zerohash trading. It's a live, continuously updated record of all open buy and sell limit orders for an instrument, organized by price, then time — so at any moment it shows exactly where the market is willing to trade.

It works the way a traditional stock or futures exchange does:

Participants place limit orders at the price they're willing to buy or sell. Open buy orders (bids) sit on one side of the book; open sell orders (asks) sit on the other.
The book ranks orders by price first — the most competitive prices sit at the top — and then by time, so earlier orders at the same price are filled first.
The matching engine pairs them up. When an incoming order's price meets an open order on the opposite side, a trade executes. If it doesn't, the order rests on the book until it's matched or canceled.

The result is a single, shared, transparent market: everyone trades against the same book, and the market price is simply where the best available buy and sell orders meet.

CLOB vs. RFQ

zerohash offers two ways to get a trade done, and they suit different needs:

CLOB is many-to-many. You place an order into a shared order book and trade against the full set of open orders from other participants. Pricing is set by the market, you can rest orders on the book, and you get full price transparency and depth. It's built for active, price-sensitive, higher-frequency trading.
RFQ (Request for Quote) is one-to-one. You request a price for a specific size, zerohash returns a firm quote, and you either take it or leave it. There's no order book and nothing rests — it's a simple, immediate "here's your price for a given period of time" flow, well suited to on-demand buy/sell and embedded consumer experiences.

In short: reach for the CLOB when you want to interact with a live market and control your execution; reach for RFQ when you just want a firm price against a period of time to trade against right now.

FIX API Integration Required

Trading on the CLOB is done over a FIX API integration, which is required to place and manage orders. The session is a bi-directional, event-driven FIX 5.0 connection, and a typical order lifecycle looks like this:

Session: Establish a FIX 5.0 session with zerohash using standard Logon (A) / Logout (5) and heartbeat messages.
Place order: Submit a new order via NewOrderSingle (D), specifying symbol, side, order type, quantity, and time in force.
Acknowledgement & fills: zerohash returns ExecutionReport (8) messages covering acknowledgement, partial fills, full fills, and terminal states.
Cancel / replace: Resting orders may be cancelled via OrderCancelRequest (F) or amended via OrderCancelReplaceRequest (G) before full execution.

When you place an order, you control its execution with these parameters:

Order Type: limit or market, supporting a range of execution strategies.
Side: buy or sell.
Time in Force: Options such as GTC, GTT, IOC, and FOK, controlling how long an order rests on the book before it fills, expires, or cancels.
Quantity: The amount to trade, entered by either quantity (units of the asset) or notional (value in the quoted currency).

REST API Integration

Same market, lighter connection. The REST API lets you submit, cancel, and query CLOB orders over standard request/response calls — no persistent session to maintain — while routing to the same order book and matching engine as FIX.
Best as a supplement. Use it for order management and operational tasks where a full FIX session isn't warranted; FIX remains the primary path for live, latency-sensitive trading. See the REST API for CLOB Trading for endpoint details.

More details can be found in the Central Limit Order Book guides.